X-ray detector for phase contrast imaging

Abstract

The invention relates to an X-ray detector ( 30 ) that comprises an array of sensitive elements (P i−1,b , P ia , P ib , P i+1,a , P i+1,b ) and at least two analyzer gratings (G 2a , G 2b ) disposed with different phase and/or periodicity in front of two different sensitive elements. Preferably, the sensitive elements are organized in macro-pixels (II i ) of e.g. four adjacent sensitive elements, where analyzer gratings with mutually different phases are disposed in front said sensitive elements. The detector ( 30 ) can particularly be applied in an X-ray device ( 100 ) for generating phase contrast images because it allows to sample an intensity pattern (I) generated by such a device simultaneously at different positions.

The invention claimed is: 
     
       1. An X-ray detector, comprising:
 an array of X-ray sensitive elements; 
 at least two analyzer gratings disposed with different phase and/or periodicity in front of two different sensitive elements of the array of X-ray sensitive elements, and 
 at least one macro-pixel consisting of a plurality of sensitive elements with analyzer gratings in front of the plurality of sensitive elements, wherein the analyzer gratings have mutually different phase and/or periodicity. 
 
     
     
       2. The X-ray detector according to  claim 1 , wherein the analyzer gratings are absorption grids. 
     
     
       3. The X-ray detector according to  claim 1 , wherein the analyzer gratings of the macro-pixel have the same periodicity but mutual phase shifts that are evenly distributed over one period. 
     
     
       4. An X-ray device for generating phase contrast images of an object, comprising:
 an X-ray source; 
 a diffractive optical element that is exposed to the X-ray source; 
 an X-ray detector with an array of X-ray sensitive elements and at least two analyzer gratings disposed with different phase and/or periodicity in front of two different sensitive elements, and; 
 a phase grating, wherein the diffractive optical element is a source grating located adjacent the x-ray source and on a first side of an object being scanned and the phase grating is located on an opposing side of the object between the object and the at least two analyzer gratings. 
 
     
     
       5. The X-ray device according to  claim 4 , wherein the periodicity of the analyzer gratings corresponds to the periodicity of an interference pattern generated by the DOE at the position of the analyzer gratings. 
     
     
       6. The X ray device according to  claim 4 , further comprising an evaluation unit for determining the phase shift caused by an object in X-rays on a path from the X-ray source to the X-ray detector. 
     
     
       7. The X ray device according to  claim 6 , wherein the evaluation unit comprises a reconstruction module for reconstructing a cross-sectional phase contrast slice image of an object from X-ray phase contrast projections of the object taken from different directions. 
     
     
       8. The X ray device according to  claim 4 , wherein the X-ray detector and/or the X-ray source are mounted to rotate with respect to a stationary object. 
     
     
       9. A method for analyzing an X-ray intensity pattern, comprising a simultaneous local sampling of an intensity pattern with analyzer gratings, wherein the analyzer gratings include at least two analyzer gratings disposed with mutually different phase and/or periodicity in front of at least one macro-pixel, consisting of a plurality of sensitive elements. 
     
     
       10. The X-ray detector of  claim 1 , wherein a first of the at least two analyzer gratings has absorbing strips that are disposed in front of a first of the two different sensitive elements and not a second of the two different sensitive elements. 
     
     
       11. The X-ray detector of  claim 10 , wherein a second of the at least two analyzer gratings has absorbing strips that are disposed in front of the second of the two different sensitive elements and not the first of the two different sensitive elements. 
     
     
       12. The X-ray detector of  claim 1 , wherein the X-ray detector includes at least four analyzer gratings, each in front of a different sensitive elements of the array of X-ray sensitive elements. 
     
     
       13. The X-ray detector of  claim 12 , wherein at least one pair of sensitive elements of the array of X-ray sensitive elements corresponds to a macro-pixel that provides simultaneous analysis of the local intensity pattern at different sampling points. 
     
     
       14. The X-ray device of  claim 4 , wherein the phase grating generates an interference pattern for radiation traversing there through. 
     
     
       15. The X-ray device of  claim 4 , wherein a first of the at least two analyzer gratings has absorbing strips that are disposed in front of a first of the two different sensitive elements and not a second of the two different sensitive elements. 
     
     
       16. The X-ray device of  claim 15 , wherein a second of the at least two analyzer gratings has absorbing strips that are disposed in front of the second of the two different sensitive elements and not the first of the two different sensitive elements. 
     
     
       17. The X-ray device of  claim 4 , wherein the X-ray detector includes at least four analyzer gratings, each in front of a different sensitive elements of the array of X-ray sensitive elements. 
     
     
       18. The X-ray device of  claim 17 , wherein at least one pair of sensitive elements of the array of X-ray sensitive elements corresponds to a macro-pixel that provides simultaneous analysis of the local intensity pattern at different sampling points. 
     
     
       19. An X-ray detector, comprising:
 an array of X-ray sensitive elements; an 
 at least two analyzer gratings disposed with different phase and/or periodicity in front of two different sensitive elements of the array of X-ray sensitive elements, 
 wherein a first of the at least two analyzer gratings has absorbing strips that are disposed in front of a first of the two different sensitive elements and not a second of the two different sensitive elements. 
 
     
     
       20. An X-ray detector, comprising:
 an array of X-ray sensitive elements; and 
 at least two analyzer gratings disposed with different phase and/or periodicity in front of two different sensitive elements of the array of X-ray sensitive elements, 
 wherein the X-ray detector includes at least four analyzer gratings, each in front of a different sensitive elements of the array of X-ray sensitive elements. 
 
     
     
       21. An X-ray device for generating phase contrast images of an object, comprising:
 an X-ray source; 
 a diffractive optical element that is exposed to the X-ray source; and 
 an X-ray detector with an array of X-ray sensitive elements and at least two analyzer gratings disposed with different phase and/or periodicity in front of two different sensitive elements, 
 wherein a first of the at least two analyzer gratings has absorbing strips that are disposed in front of a first of the two different sensitive elements and not a second of the two different sensitive elements. 
 
     
     
       22. An X-ray device for generating phase contrast images of an object, comprising:
 an X-ray source; 
 a diffractive optical element that is exposed to the X-ray source; and 
 an X-ray detector with an array of X-ray sensitive elements and at least two analyzer gratings disposed with different phase and/or periodicity in front of two different sensitive elements, 
 wherein the X-ray detector includes at least four analyzer gratings, each in front of a different sensitive elements of the array of X-ray sensitive elements.